We have started experiments designed to clarify the association of the Epstein-Barr Virus (EBV) genome and human chromosomes. Using somatic-cell hybrids of mouse (CLID) and Burkitt tumor cells (HR-1) we have shown that the EBV genome is not associated with all human chromosomes in the resulting hybrid (CLID/HR-1). Further studies will be performed to determine which chromosome(s) the genome is associated with. We will continue our studies concerned with the maintenance of the EBV genome in its "repressed" state and the control and regulation of EBV functions by the host cell. We will attempt to characterize the mechanism involved with the inhibitory activity associated with a particle free extract of D98 cells; i.e., one of the parent cell lines of the Burkitt hybrid, D98/HR-1. Attempts will be made to purify the inhibitory product and elucidate the blocking mechanism(s) observed against the replication of both EBV and cytomegalovirus. Our studies, concerned with the observation that EBV DNA synthesis is resistant to hydroxyurea (Hu), will be continued. We are presently trying to determine if EBV codes for a new Hu resistant ribonucleotide reductase.